1. Field of the Invention
The present invention relates to an image forming apparatus that performs a wireless communication with a radio tag attached to a document or a recording medium on which an image of the document is to be formed.
2. Description of the Related Art
Recently, along with improvements in the image quality of image forming apparatuses (such as digital copying machines and copiers), there is an increasing risk of copying to forge documents with respect to specific documents such as bank notes and securities, for which copying is prohibited. Therefore, an image processor has been proposed, which corrects the characteristic of an input color image signal, extracts the characteristic in the obtained corrected image signal, to determine the similarity between the extracted characteristic and the characteristic of a prepared specific document, and changes the processing content of the input color image signal corresponding to the similarity (see, for example, Japanese Patent Application Laid-Open No. H6-105136).
Furthermore, there is an image recognizing apparatus that registers image patterns of specific documents beforehand, compares an input image pattern with the registered image patterns to determine the similarity, and determines whether the input image is the one of a specific document based on the determined similarity, to prevent the specific document from being forged (see, for example, Japanese Patent Application Laid-Open Nos. H2-210591 and H6-54186).
Meanwhile, ID element (Radio Frequency Identification (RFID)) technology for holding individual information electronically, to transmit information by electromagnetic induction in a non-contact manner has been developed, and adapted for identification control of goods. The individual recognizing method using the ID element is attracting attention as a technique replacing barcodes in the distribution industries (see, for example, “Putting Information to Things: RFID Tags and Their Applications”, by SHIIO Ichiro and HAYASAKA Toru, Journal of Information Processing, August 1999, Vol. 40, No. 8, pp. 846 to 850).
Particularly, forgery of cash vouchers, concert tickets and the like can be prevented by storing special coded data in a radio tag. Furthermore, the radio tag attached to the cash vouchers, concert tickets and the like has an antenna built in an LSI, the communication distance with a reader/writer is as short as one millimeter to several centimeters.
As another method for preventing copy of bank notes or securities, there is a method such that, at the time of copying bank notes or securities, a tracking pattern indicating information specifying the type of machine or the machine number of an image forming apparatus that made the copy is added to the image of the bank notes or securities and output. Accordingly, forgery of bank notes or securities by copying the bank notes or securities can be prevented.
Furthermore, due to recent popularization of information technology (IT) including the Internet and personal computers (PCs), various types of electronic information is created in the intelligent manufacturing activities, and the information is output onto a recording medium such as paper and overhead projector (OHP) sheets by an image forming apparatus such as a copying machine and a printer. The output paper or document is distributed in meetings and the like as information sharing means, and is used in the intelligent manufacturing activities. The distributed paper or document is brought home by the recipient, and stored as it is, or converted to a Joint Photographic Experts Group (JPEG) image file by an image reader such as a scanner, and stored. To use the information as an information source for further intelligent manufacturing activities, the distributed paper or document is further copied, directly output from the converted JPEG image file, or the image file is processed by a personal computer and output. Thus, while the received paper or document is analog information, it is desired to handle it as digital information to reuse or reprocess the information, and the conversion from the analog information to the digital information is performed by using an optical image reader.
However, in the conventional technique, the recent high quality image of printers enables forgery of securities and cash vouchers. To prevent the forgery, a technique for embedding a radio tag in the securities and cash vouchers has been known, but basically, read and write of the content of the radio tag is possible. Accordingly, forgery of the radio tag itself is possible, though not so easy.
According to the image forming apparatus using the forgery prevention technique, forgery becomes difficult, but a method in which an image is read by a simple personal image reader such as a scanner, and the image is formed and forged by the image forming apparatus can be considered. For example, the securities or cash vouchers can be color-printed on a white paper in which the radio tag is embedded. Hence, it is necessary to prevent such forgery.
When the distributed paper or document is copied, there is a disadvantage in that there is only analog information on the document, and the image quality is deteriorated inevitably at the time of converting the analog information to the digital information by the image reader. That is, texts, graphs, tables, and images are present together on a document, but the image reader obtains the digital information, assuming all of these as image information. However, at the time of optical conversion by the image reader, deterioration in the image quality occurs due to physical factors such as modulation transfer function (MTF) characteristic of lenses or a charge coupled device (CCD). Furthermore, the image information has a large amount of information, and compression according to image processing such as image compression is generally used. However, there is a problem in that deterioration in the image quality occurs depending on the compressibility in the image compression. Furthermore, texts included in the document can be extracted as text data according to image processing by, for example, an optical character reader (OCR), but there is a problem in that deterioration in the information quality from the document due to the conversion accuracy occurs.
Furthermore, to use the information distributed as paper or document, there are several methods, that is, to create electronic information newly by a PC by referring to the paper or document, to fetch the information as an image file such as the JPEG image file by using an image reader, and to obtain the electronic information of the document itself by inquiring the information originator. However, those methods require time and labor. In other words, the document is electronically created by the originator by using a PC, and output by a printer, and hence, there is the electronic information of the document itself. While the electronic information can be distributed together with the document, since it is necessary to distribute the information by storing the information on another recording medium such as floppy disk (FD), CD-ROM, or CD-R, or to transmit the information in e-mails via the Internet separately. Accordingly, it requires time and labor to distribute the electronic information.
Recently, along with improvements in the image quality of the image forming apparatuses such as copying machines, when a book or the like is copied by a copying machine in public libraries or corporate libraries, there is a problem of infringing on the copyright of a publisher by copying the book.